Engine system and a method of manufacturing same

Abstract

An engine system is disclosed in which the transfer of heat from pressurized oil flowing through an integrally formed oil transfer passage of the engine is reduced by providing a thermal barrier between the oil and the engine. In one example the thermal barrier is provided by the use of a thick walled plastic tube and in other embodiments ribs are used to separate an oil flow passage from the engine.

The invention claimed is: 
     
       1. An engine system, comprising:
 an oil transfer passage having a thermal barrier interposed between oil and the engine, the thermal barrier comprising:
 a plastic tube having a low thermal conductivity positioned in the oil transfer passage, 
 wherein the plastic tube defines an oil flow passage through which oil pressurized by an oil circulation pump flows in use. 
 
 
     
     
       2. The system of  claim 1 , wherein the plastic tube has a number of external ribs formed thereon to space it from a wall defining the oil transfer passage, wherein the low thermal conductivity of the thermal barrier is lower than a thermal conductivity of any metal comprising the engine. 
     
     
       3. The system of  claim 2 , wherein the external ribs extend longitudinally along the plastic tube. 
     
     
       4. The system of  claim 2 , wherein the external ribs extend circumferentially around the plastic tube. 
     
     
       5. The system of  claim 4 , wherein:
 the external ribs define a number of compartments forming part of the thermal barrier; 
 one or more of the number of compartments comprise an aperture through which oil may exit the plastic tube prior to reaching an end of the plastic tube. 
 
     
     
       6. The system of  claim 2 , wherein the plastic tube has an inner plastic tube and an outer plastic tube is spaced apart from the inner plastic tube by the external ribs. 
     
     
       7. The system of  claim 6 , wherein the inner plastic tube defines an oil flow passage through which the oil pressurized by the oil circulation pump flows, and the outer plastic tube has an outer surface engaging with a wall defining the respective oil transfer passage. 
     
     
       8. The system of  claim 1 , further comprising a closed cell foam tube coupled to the plastic tube and made from a material having a low thermal conductivity. 
     
     
       9. The system of  claim 8 , wherein the closed cell foam tube has an outer surface in contact with the oil transfer passage and a bore defining an oil flow passage through which oil flows in use. 
     
     
       10. The system of  claim 8 , wherein the closed cell foam tube is fitted over the plastic tube defining an oil flow passage through which oil flows in use. 
     
     
       11. The system of  claim 8 , wherein the closed cell foam tube is fitted over the plastic tube defining an oil flow passage, the system further comprising an outer tube fitted over the closed cell foam tube such that the closed cell foam tube is interposed between the plastic tube and the outer tube. 
     
     
       12. The system of  claim 1 , wherein:
 the engine has a cylinder block and at least one oil transfer passage is a main gallery formed in the cylinder block of the engine; 
 the oil transfer passage includes a closed cell foam tube coupled between the plastic tube and an inner wall of the oil transfer passage; and 
 the oil transfer passage comprises at least one or more apertures which allow the flow of oil out of the plastic tube and closed cell foam tube and into at least one main bearing of the engine. 
 
     
     
       13. The system of  claim 1 , wherein:
 the engine has a cylinder head and the at least one oil transfer passage is an oil supply gallery formed in the cylinder head of the engine; 
 the oil transfer passage includes a closed cell foam tube coupled between the plastic tube and an inner wall of the oil transfer passage; and 
 the oil transfer passage comprises at least one or more apertures which allow the flow of oil out of the plastic tube and closed cell foam tube and into at least one camshaft bearing of the engine. 
 
     
     
       14. A method for flowing oil, comprising:
 pumping oil from a sump to a cylinder block transfer passage to deliver oil to a crankshaft, including flowing oil through a plastic tube positioned in the cylinder block transfer passage. 
 
     
     
       15. The method of  claim 14 , further comprising after exiting the plastic tube, flowing oil from out through a bearing supply passage without a plastic tube. 
     
     
       16. The method of  claim 14 , wherein the plastic tube is positioned longitudinally along the oil transfer passage parallel with the crankshaft. 
     
     
       17. The method of  claim 14 , wherein the bearing supply passage is positioned vertically, the method including flowing oil vertically downward to the crankshaft. 
     
     
       18. The method of  claim 17 , wherein the flowing oil is delivered through the oil transfer passage by a circulation pump driven by an engine during an engine cold start operation, wherein the plastic tube comprises an inner plastic tube and an outer plastic tube spaced apart from the inner plastic tube by longitudinally extended external ribs, the oil flowing only through the inner plastic tube, wherein the plastic tube has a plurality of downward-opening apertures, and wherein the apertures of the plastic tube are connected to bearing supply passages. 
     
     
       19. A system, comprising:
 a metal engine block having a longitudinally positioned crankshaft therein; 
 a longitudinal oil passage with a plurality of parallel outlets opening to crankshaft journal bearings, the longitudinal oil passage including an internal plastic tube positioned therein between oil and the metal engine block, the outlets passing through the plastic tube and passing through the metal engine block without any plastic insulator therein. 
 
     
     
       20. The system of  claim 19 , wherein an outer wall of the internal plastic tube is flush with an inner wall of the longitudinal oil passage, excepting for the plurality of parallel outlets. 
     
     
       21. The system of  claim 19 , further comprising:
 a closed cell foam tube positioned between the internal plastic tube and the longitudinal oil passage, wherein the outlets pass through the closed cell foam tube without any plastic insulator therein. 
 
     
     
       22. The system of  claim 21 , further comprising
 an outer plastic tube positioned between the closed cell foam tube and the longitudinal oil passage, wherein the outlets pass through the outer plastic tube without any plastic insulator therein. 
 
     
     
       23. The system of  claim 22 , wherein the internal plastic tube comprises a plurality of deflectable barbs configured to allow insertion of the internal plastic tube into a bore of the closed cell foam tube in a first direction, and further configured to engage the bore of the closed cell foam tube when the internal plastic tube is moved within the closed cell foam tube in a second direction, opposite the first direction.